I can address the -f operator. It is used to format a string. You can specify how to format a series of numeric or alphanumeric values.On the left side of the operator you specify the formatting and on the right is the comma-separated value list.
In your example the formatting instruction (left side of -f) is the syntax that includes {0}, {1}, etc. Each of these will be replaced by the values on the right side of the -f operator - $variable1, $variable2, etc.
As for why there is not data, using ALZDBAs' Write-Host syntax should help.
Hope this helps you and good luck with Powershell. It is an amazing tool!
MG
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